Problem: Nadia has taken 4 exams and her average score so far is 79. If she gets 100, a perfect score, on the remaining 2 exams, what will her new average be?
Explanation: If she gets 100 on the remaining exams, the sum of her scores will be $4 \cdot 79 + 2 \cdot 100 = 516$ Her overall average will then be $516 \div 6 = 86$.